Self Fixturing Assembly Techniques

ABSTRACT

A process, apparatus, and system for joining at least two workpieces together using at least two adhesives each having substantially different cure times. A first adhesive having a first cure time is used to form a first bond between the two workpieces, the first adhesive having a first cure time. A second adhesive having a second cure time, the second cure time being substantially shorter than the first cure time is used to form a fixturing bond. The fixturing bond maintaining the first and second workpieces in position prior to the first adhesive curing.

CROSS REFERENCE TO RELATED APPLICATIONS

This patent application is related to and incorporates by reference intheir entireties for all purposes the following patent applicationsfiled on Oct. 16, 2009:

-   (i) U.S. patent application Ser. No. 12/580,914 entitled “PORTABLE    COMPUTER DISPLAY HOUSING” by Bergeron et al., now U.S. Pat. No.    8,233,109;-   (ii) U.S. patent application Ser. No. 12/580,985 entitled “PORTABLE    COMPUTER ELECTRICAL GROUNDING AND AUDIO SYSTEM ARCHITECTURES” by    Thomason et al.;-   (iii) U.S. patent application Ser. No. 12/580,946 entitled “PORTABLE    COMPUTER HOUSING” by Casebolt et al.;-   (iv) U.S. patent application Ser. No. 12/580,934 entitled “METHOD    AND APPARATUS FOR POLISHING A CURVED EDGE” by Lancaster et al. that    takes priority under 35 U.S.C. 119(e) to U.S. Provisional Patent    Application Ser. No. 61/249,200 entitled “COMPLEX GEOGRAPHICAL EDGE    POLISHING” by Johannessen filed Oct. 6, 2009 and incorporated by    reference in its entirety;-   (v) U.S. patent application Ser. No. 12/580,922 entitled “COMPUTER    HOUSING” by Raff et al., now U.S. Pat. No. 8,111,505;-   (vi) U.S. patent application Ser. No. 12/580,976 entitled “BATTERY”    by Coish et al., now U.S. Pat. No. 8,199,469, which is a    continuation in part of U.S. patent application Ser. No. 12/549,570    filed Aug. 28, 2009;-   (vii) U.S. patent application Ser. No. 12,580,886 entitled “PORTABLE    COMPUTER DISPLAY HOUSING” by Bergeron et al.; and-   (viii) U.S. patent application Ser. No. 12/580,927 entitled    “COMPUTER HOUSING” by Raff et al., now U.S. Pat. No. 8,199,468.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The described embodiments relate generally to manufacturing assemblyoperations. More particularly, the present embodiments relate to joiningcomputer sub-assemblies together in a manner that is both operationallyefficient as well as preserves the aesthetic aspects.

2. Description of the Related Art

The outward appearance of a portable computing device, including itsdesign and its heft, is important to a user of the portable computingdevice, as the outward appearance contributes to the overall impressionthat the user has of the portable computing device. At the same time,the assembly of the portable computing device is also important to theuser, as a durable assembly will help extend the overall life of theportable computing device and will increase its value to the user.

One design challenge associated with the portable computing device isthe design of the enclosures used to house the various internalcomponents. This design challenge generally arises from a number ofconflicting design goals that include the desirability of making theenclosure lighter and thinner, the desirability of making the enclosurestronger and making the enclosure more aesthetically pleasing. Thelighter enclosures, which typically use thinner plastic structures andfewer fasteners, tend to be more flexible and therefore they have agreater propensity to buckle and bow when used while the stronger andmore rigid enclosures, which typically use thicker plastic structuresand more fasteners, tend to be thicker and carry more weight.Unfortunately, increased weight may lead to user dissatisfaction, andbowing may damage the internal parts.

Furthermore, in most portable computing devices, the enclosures aremechanical assemblies having multiple parts that are screwed, bolted,riveted, or otherwise fastened together at discrete points. For example,the enclosures typically have included an upper casing and a lowercasing that are placed on top of one another and fastened together usingscrews. These techniques typically complicate the housing design andcreate aesthetic difficulties because of undesirable cracks, seams, gapsor breaks at the mating surfaces and fasteners located along thesurfaces of the housing. For example, a mating line surrounding theentire enclosure is produced when using an upper and lower casing. Notonly that, but assembly is often a time consuming and cumbersomeprocess. For example, the assembler has to spend a certain amount oftime positioning the two parts and attaching each of the fasteners.Furthermore, assembly often requires the assembler to have special toolsand some general technical skill.

Another challenge is in techniques for mounting structures within theportable computing devices. Conventionally, the structures have beenlaid over one of the casings (upper or lower) and attached to one of thecasings with fasteners such as screws, bolts, rivets, etc. That is, thestructures are positioned in a sandwich like manner in layers over thecasing and thereafter fastened to the casing. This methodology suffersfrom the same drawbacks as mentioned above, i.e., assembly is timeconsuming and cumbersome.

Therefore, it would be beneficial to provide a housing for a portablecomputing device that is aesthetically pleasing and lightweight, durableand yet environmentally friendly. It would also be beneficial to provideoperationally efficient methods for mounting computer sub-assemblies tothe housing that preserves the aesthetic look and feel of the housing.

SUMMARY OF THE DESCRIBED EMBODIMENTS

This paper describes various embodiments that relate to systems,methods, and apparatus for mounting computer sub-assemblies to alightweight, visually seamless housing suitable for use in portablecomputing applications.

A self-fixturing method for bonding at least two workpieces together isdescribed. The method can be carried out by performing at least thefollowing operations. Forming a first bond between the two workpiecesusing a first adhesive, having a first cure time and self-fixturing thetwo workpieces together by bonding the two workpieces together using asecond adhesive having a second cure time substantially shorter than thefirst cure time. In the described embodiment, the second bond isindependent of the first bond and enables the self-fixtured workpiecesto undergo processing that would otherwise occur only after the firstadhesive has cured.

In one aspect, a first one of the workpieces is a plastic computerhousing having at least a top cover and formed of a plastic materialsuch as PCABS. A second workpiece is a metal frame formed of magnesiumor magnesium alloy having a plurality of attachment features that cantake the form of holes in the metal frame. The metal frame providingsupport for internal components of a computer assembly placed in thecomputer housing. The first adhesive can be an epoxy having a cure timeof about 12-24 hours and the second adhesive can be a UV cure gluehaving a cure time of about 5 seconds.

In one embodiment, a method for joining a first and second workpiecetogether is described. The method can be performed by carrying out atleast the following operations. Applying a first adhesive to the firstworkpiece or the second workpiece at an application region, the firstadhesive having an associated first cure time; placing the first and thesecond workpiece in contact with each other at the application region;applying an externally generated compression force to the first and thesecond workpieces; applying a second adhesive to at least one of thefirst and second workpieces at an attachment feature, the secondadhesive having an associated cure time substantially less than thefirst cure time; curing the second adhesive; and removing the externallygenerated compression force.

Computer readable medium encoded with computer program executed by aprocessor for controlling a manufacturing process for joining a firstand second workpiece together is described. The computer readable mediumincluding computer code for applying a first adhesive to the firstworkpiece or the second workpiece at an application region, the firstadhesive having an associated first cure time; computer code for placingthe first and the second workpiece in contact with each other at theapplication region; computer code for applying an externally generatedcompression force to the first and the second workpieces; computer codefor applying a second adhesive to at least one of the first and secondworkpieces at an attachment feature, the second adhesive having anassociated cure time substantially less than the first cure time;computer code for curing the second adhesive; and computer code forremoving the externally generated compression force.

Other aspects and advantages of the described embodiments will becomeapparent from the following detailed description taken in conjunctionwith the accompanying drawings which illustrate, by way of example, theprinciples of the described embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

The embodiments will be readily understood by the following detaileddescription in conjunction with the accompanying drawings, wherein likereference numerals designate like structural elements, and in which:

FIG. 1 shows how in one embodiment describing computer top cover inaccordance with the described embodiments.

FIG. 2 shows rear frame in accordance with the described embodiments.

FIG. 3 shows representative example of first adhesive applied to rearframe.

FIG. 4 shows rear frame placed in contact with computer housing prior toinsertion into compression fixture.

FIG. 5 shows rear frame and computer housing in compression fixture andUV glue applicator in accordance with the described embodiments.

FIG. 6 shows a representative plug created by cured UV glue.

FIG. 7 shows a flowchart detailing a process in accordance with theembodiments.

DETAILED DESCRIPTION OF SELECTED EMBODIMENTS

Reference will now be made in detail to representative embodimentsillustrated in the accompanying drawings. It should be understood thatthe following descriptions are not intended to limit the embodiments toone preferred embodiment. To the contrary, it is intended to coveralternatives, modifications, and equivalents as may be included withinthe spirit and scope of the described embodiments as defined by theappended claims.

The following relates to a process, apparatus, and system for joining atleast two workpieces together using at least two adhesives each havingsubstantially different cure times. In one embodiment, a first adhesivecan have an associated first cure time and a second adhesive can have anassociated second cure time that is substantially shorter in durationthan the first cure time. For example, the first adhesive can take theform of an epoxy such as LOCTITE® H8000™ having a structural cure timeof about 24 hours at room temperature (i.e., about 25° C.) whereas thesecond adhesive can take the form of a UV cure type adhesive such asLOCTITE® 3106™ having a cure time of about 3-10 seconds to about 30seconds when exposed to UV light having wavelength in the range of about280-395 nm. The second adhesive can act to self fixture the first andsecond workpieces together as a single piece that can immediatelyundergo subsequent processing without the need for an external fixturingdevice. In this way, at least an amount of time approximately equal tothe difference between the first and second cure times can be saved fromthe overall processing time.

These and other embodiments are discussed below with reference to FIGS.1-7. However, those skilled in the art will readily appreciate that thedetailed description given herein with respect to these figures is forexplanatory purposes as the full extent of the embodiments goes beyondthe embodiments described in this paper.

FIG. 1 shows how in one embodiment describing computer top cover 100, afirst workpiece can take the form of computer housing 102 and a secondworkpiece can take the form of metal frame 104 bonded to interiorsurface 106 of computer housing 102. In the described embodiment,computer top cover 100 can be part of a portable, lightweight yet sturdyportable computing system, such as a laptop computer. In order to keepthe overall weight of the portable computing system at a minimum,housing 102 can be formed of lightweight and resilient material alongthe lines of PCABS. However, due to the relative fragility of anycomputer housing composed solely of plastic, even plastic as rugged asPCABS, additional structural support can be provided. The additionalstructural support for top cover 100 can be provided by, for example,front frame 108. Support for a user interface such as a touch pad can beprovided by touch pad frame 110 that can be formed of a metal such asaluminum, magnesium, or any alloys thereof. Attraction plates 112 can beused in conjunction with magnets to secure a lid to top cover 100 whenthe lid is placed in a closed position.

Rear frame 104 can provide support for a rear portion of housing 102 aswell as, in some embodiments, a user interface such as a keyboard (shownin silhouette). Rear frame 104 can also act as a platform onto which anumber of internal components such as a main logic board, or MLB,optical disk drive, or ODD, and so on can be mounted. Rear frame 104 canbe formed of lightweight and strong material along the lines ofaluminum, magnesium, or any alloy thereof. In the described embodiment,rear frame 104 and housing 102 can be bonded together using a selffixturing technique in accordance with the described embodiments. Forexample, to form a first bond, a first adhesive (such as epoxy) having afirst cure time can be applied to an inside surface of rear frame 104.However, securing together housing 102 and rear frame 104 using aconventional bonding technique requires that both rear frame 104 andhousing 102 be placed in a compression fixture at least until the firstadhesive has cured. In this way, rear frame 104 and housing 102 cannotbe removed from the compression fixture for further processing at leastuntil after the first adhesive has cured wasting valuable processingtime that could otherwise be used for subsequent processing. It shouldalso be noted that compressing housing 102 for any appreciable length oftime can also cause deformations and warping in top cover 100.

However, using a self fixturing technique in accordance with thedescribed embodiments, the operational inefficiencies and potentialproduct damage associated with a conventional bonding approach can beessentially eliminated. For example, while the rear frame 104 andhousing 102 are still in the compression fixture, a second, or selffixturing, bond that is independent of the first bond can be formedbetween rear frame 104 and housing 102. The fixturing bond can be formedusing a second adhesive having a shorter cure time than the firstadhesive. The fixturing bond can be formed by applying a second adhesiveat any of a number of attachment features 114 located in rear frame 104.In the described embodiment attachment features 114 can take the form ofperforations along the lines of circular holes each having diameter D1being a size that allows a sufficient amount of surface 106 to be wettedby the second adhesive passing through attachment feature 114. Thesecond adhesive can cure in a period of time much less than the timerequired for the first adhesive to cure and can form semi-spherical-likeplugs 116 each having a diameter D2 that can be greater than diameterD1. In this way, the bond formed by the second adhesive can quicklysecure rear frame 104 and housing 102 while still in the compressionfixture. However, once the fixturing bond is created, rear frame 104 andhousing 102 can be immediately removed from the compression fixturewithout fear of disturbing the curing of the first adhesive. Moreover,the tight fit and unyielding nature of plugs 116 can help to maintainthe compressive force (i.e., sometimes referred to as being “frozen intoplace”) between rear frame 104 and housing 102 even after being removedfrom the compression fixture.

A particular embodiment will now be described with reference to FIGS.2-6. More specifically, FIG. 2 shows rear frame 200 in accordance withthe described embodiments. In particular, FIG. 2 illustrates aparticular approach to applying the first adhesive in the form of epoxy202 to interior surface 204 of rear frame 200. Epoxy 202 can take theform of a two part type epoxy along the lines of LOCTITE® H8000™manufactured by Henkel AG & Co. of Dusseldorf, Germany having a curetime at 25° C. of about one hour. Epoxy 202 can be applied to interiorsurface 204 in any number of ways. For example, as shown in FIG. 3,epoxy 202 can be applied to rear frame 200 by way of dispenser unit 300.Rear frame 200 can be placed on platen 302 having interior surface 204facing epoxy dispenser nozzle 304. The position of epoxy dispensernozzle 304 can be automatically controlled by, for example, a computer.In this way, epoxy 202 can be applied in any manner and in any amountand in any location on interior surface 204 deemed appropriate toachieve the most effective bond between rear frame 200 and housing 102.

Once epoxy 202 is properly applied to surface 204, rear frame 200 can beremoved from epoxy dispensing unit 300 and placed “epoxy side” down ontosurface 106 as shown in FIG. 4. Once rear frame 200 and housing 102 arein proper placement, rear frame 200 and housing 102 can be placed intocompression fixture 500 as illustrated in FIG. 5. In the describedembodiment, compression fixture 500 can generate compression force CFthat can be applied by compression fixture 500 to housing 102 and rearframe 200. In this way, compression force CF can squeeze epoxy 202between housing 102 and rear frame 104 causing epoxy 202 to wet out.

While still in compression fixture 500 and with attachment features 114accessible via access holes 502, second adhesive in the form of UV gluealong the lines of LOCTITE® 3106™ can be applied by dispenser unit 504through access holes 502 each associated with a specific one ofattachment features 114. Once the second adhesive is applied,compression fixture 500, housing 102 and rear flame 200 can be placed ina UV cure system that can generate UV light in the range of about280-395 nm. In this way, the UV glue can cure in about 5 seconds formingplug 600 an example of which is shown in FIG. 6. In this way, housing102 and rear frame 200 are essentially locked, or frozen, into placesuch that epoxy 202 can still remain in a compressed state being heldbetween housing 102 and rear frame 200 even though removed entirely fromcompression fixture 500. Once removed, the housing 102 and rear frame200 (now essentially in the form of top cover 100) can undergosubsequent processing that would otherwise have to wait for epoxy 202 tocure (which in this case could be as long as one hour). Accordingly, anyneed for ovens to cure epoxy 202 can be eliminated and the overall timeto process top cover 100 can be reduced by at least the amount of timeheretofore wasted waiting for epoxy 202 to cure.

FIG. 7 shows a flowchart of process 700 in accordance with the describedembodiments. Process 700 can be used to fabricate assemblies in a costeffective and efficient manner. In particular, the process describes inpart the joining of at least two workpieces by adhesives havingsubstantially different cure times, a primary adhesive having a longercure time than a secondary adhesive. The primary adhesive providing theprimary bond between the two workpieces and the secondary adhesiveproviding a self fixturing function as well as providing additional bondstrength to the primary bond. The self fixturing effectively allowingthe assembly of the joined workpieces to continue with post joiningoperations which heretofore had to wait at least until the primaryadhesive cured. Process 700 can be carried out by performing at leastthe following operations. At 702, a first adhesive having an associatedfirst cure time can be applied to either a first or a second workpieceat an application area. In the described embodiment, the first adhesivecan take the form of a two part epoxy having a cure time in the range ofa few hours.

At 704, the first and second workpieces can be placed in contact witheach other at the application area. In this way, the first adhesive canmake contact with both the first and the second workpiece. Next, at 706,an externally generated compression force is applied to both the firstand second workpieces. In this way, the first adhesive can properly “wetup” between the first and second workpieces so as to at least remove anyvoids and so on that could have an adverse affect on the bond formed. At708, a second adhesive having a second cure time that is shorter thanthe first cure time is applied such that the second adhesive comes incontact with both the first and the second workpieces. It should benoted that the application of the second adhesive can take place whilethe externally generated compression force is still being applied to thefirst and the second workpieces. In the described embodiment, the secondadhesive can take the form of a UV cure glue having a cure time of about10 seconds.

At 710, the second adhesive is cured. For example, if the secondadhesive is a UV cure glue (such as LOCTITE® 3106™ manufactured byHenkel AG & Co. of Dusseldorf, Germany), then the first and secondworkpieces can be placed in a UV cure system for at least the amount oftime required to cure the second adhesive (about 5 seconds under UVlight of about 280-395 nm). Once the second adhesive has fully cured,the externally generated compression force can be removed at 712 and at714 the conjoined (by virtue of the second bond formed by the curedsecond adhesive) first and second workpieces can undergo subsequentprocessing that would otherwise have to wait until at least the firstadhesive had cured.

The various aspects, embodiments, implementations or features of thedescribed embodiments can be used separately or in any combination.Various aspects of the described embodiments can be implemented bysoftware, hardware or a combination of hardware and software. Thedescribed embodiments can also be embodied as computer readable code ona computer readable medium for controlling assembly operations or ascomputer readable code on a computer readable medium for controlling amanufacturing line used to fabricate housings. The computer readablemedium is any data storage device that can store data which canthereafter be read by a computer system. Examples of the computerreadable medium include read-only memory, random-acess memory, CD-ROMs,DVDs, magnetic tape, optical data storage devices, and carrier waves.The computer readable medium can also be distributed overnetwork-coupled computer systems so that the computer readable code isstored and executed in a distributed fashion.

1. A method for joining a first workpiece and a second workpiecetogether, wherein the first workpiece has at least one hole, the methodcomprising: applying a first adhesive to the first workpiece at anapplication region; placing the first workpiece in contact with thesecond workpiece at the application region; applying a second adhesiveto the first workpiece within the at least one hole; and curing thesecond adhesive before the first adhesive is fully cured.
 2. The methoddefined in claim 1, further comprising: performing additional assemblyoperations after the second adhesive is cured and before the firstadhesive is fully cured.
 3. The method defined in claim 1 wherein thefirst workpiece comprises a computer frame and wherein applying thefirst adhesive to the first workpiece comprises applying the adhesive tothe computer frame.
 4. The method defined in claim 1 wherein the secondworkpiece comprises a computer housing and wherein placing the firstworkpiece in contact with the second workpiece at the application regioncomprises placing the first workpiece in contact with the computerhousing at the application region.
 5. The method defined in claim 1wherein the at least one hole comprises a plurality of attachmentfeatures and wherein applying the second adhesive to the first workpiecewithin the at least one hole comprises applying the second adhesive tothe first workpiece within each attachment feature in the plurality ofattachment features.
 6. The method defined in claim 1 furthercomprising: after placing the first workpiece in contact with the secondworkpiece at the application region, applying a compression force to thefirst and second workpieces with a compression fixture.
 7. The methoddefined in claim 6 further comprising: after curing the second adhesive,removing the compression force from the first and second workpieces. 8.The method defined in claim 1 wherein the first adhesive comprises anepoxy and wherein applying the first adhesive to the first workpiece atthe application region comprises applying the epoxy to the firstworkpiece at the application region.
 9. The method defined in claim 1wherein the second adhesive comprises UV cure adhesive and whereinapplying the second adhesive to the first workpiece within the at leastone hole comprises applying the UV cure adhesive to the first workpieceat the application region.
 10. A computer assembly, comprising: acomputer frame having at least one hole; a computer housing; a firstadhesive in contact with the computer frame and the computer housing,wherein the first adhesive has a first cure time; and a second adhesivewithin the at least one hole and in contact with the computer housing,wherein the second adhesive has a second cure time and wherein the firstcure time is longer in than the second cure time.
 11. The computerassembly defined in claim 10 wherein the first adhesive comprises anepoxy.
 12. The computer assembly defined in claim 10 wherein the secondadhesive comprises a UV cure adhesive.
 13. The computer assembly definedin claim 10 wherein the computer frame comprises metal.
 14. The computerassembly defined in claim 10 wherein the at least one hole comprises aplurality of attachment features.
 15. The computer assembly defined inclaim 10 wherein the second adhesive within the at least one hole formsa plug that presses the computer frame and the computer housingtogether.
 16. A method for forming a computer assembly, comprising:forming a first bond between a computer frame and a computer housingusing a first adhesive; applying a compression force to the computerframe and the computer housing to compress the first adhesive; forming asecond bond between the computer frame and the computer housing using asecond adhesive; and after the second adhesive has cured and before thefirst adhesive has cured, removing the compression force.
 17. The methoddefined in claim 16 wherein forming the second bond comprises applyingthe second adhesive to a plurality of attachment features in thecomputer frame to form the second bond between the computer frame andthe computer housing at the attachment features.
 18. The method definedin claim 16, further comprising: performing subsequent processing stepson the computer assembly after the second adhesive has cured and beforethe first adhesive has cured.
 19. The method defined in claim 16 furthercomprising: while applying the compression force to the computer frameand the computer housing, exposing the second adhesive to UV light tocure the second adhesive.
 20. The method defined in claim 16 whereinforming the second bond comprises filling at least one hole in thecomputer frame with the second adhesive to form a plug in the at leastone hole, wherein the plug is configured to compress the computer frameagainst the computer housing while the first adhesive cures.